The term “cockpit” as used in the present disclosure is intended to encompass not only a cockpit in an aircraft, but also a driver's cab in a train, a bridge on a ship, and any compartment in which an operator has the ability of controlling the operation of a vehicle.
Recently the danger of aggressive acts by persons in an aircraft has increased, particularly in commercial passenger aircraft. Such aggressive acts including terrorizing acts and hijacking attempts, endanger not only individual passengers, but the entire aircraft with all persons on board. Already the possibility of an uncontrolled access by unauthorized persons into the cockpit can endanger the safety of the operation and the life of the passengers. This danger occurs not only in aircraft, but also in the unauthorized operation of public transportation vehicles such as trains, buses, ships, ferries and the like. In all these instances the passengers and crew are endangered. In practice, the danger situation always becomes critical where there are no suitable countermeasures to prevent an intruder from gaining access to the controls in the cockpit.
For an improved protection of the cockpit it is, for example known to make the doors into the cockpit in an aircraft of bulletproof materials. Such a feature provides an increased passive protection. However, bulletproof doors do not provide any possibility for actively fighting an intruder or at least to eliminate the intruder's ability to cause damage.
It is known, for example in banks and other security critical buildings or facilities to provide access through a security passage which encloses a closeable and lockable space that prevents entry into a critical area in response to certain criteria. A security passage has the advantage that a person or persons in the passage can be observed prior to being admitted into the critical area. The observation may be visual by a guard, or by a camera and display in a controlled area, or by other sensors. Furthermore, in case of danger it is possible to activate the closing and locking functions of the security passage to thereby actively fight intruders. A simple example of such a security passage is a so-called vestibule in buildings. Such a vestibule comprises two conventional hinged doors, one at each end, that can be locked so that a person in the space between the doors is trapped, so to speak. Such doors, however require a certain space for their installation and for the spacing between the doors. Such a space is normally not available in passenger conveyances, particularly in a passenger aircraft.
Other conventional safety passages are equipped with sliding doors for closing or sealing off substantial surface areas. Moreover, when such doors need to open or close, each door needs to be controlled individually and requires extra space for its retraction. For the purposes of the invention, it would be necessary to reinforce the sliding doors to protect the large sliding door surfaces against destructive impacts, for example by bullets, and they must be fire resistant. These requirements call for respective reinforcements which in connection with sliding doors result in substantial weight increases. Moreover, the individual automatic control of the operation of the sliding doors and the enforcement of a synchronism in the door motions require a relatively expensive control system, not to mention the weight problem.
A further passage concept uses a revolving door which is primarily effective as a heat-saving closure device that separates a space inside a building from the outside atmosphere. Additionally, or simultaneously, such revolving doors depend for their operation on the force applied by the user, whereby these doors revolve best when people entering the building and people exiting from the building pass through the revolving door simultaneously. Such revolving doors have a circular cross-section and are divided into individual sectors that extend radially outwardly from a central rotational axis. The sectors together form a revolving cylinder. The cylinder side walls are sealed by brushes or flexible moldings which separate the outside atmosphere from the air in the space to which the revolving door provides access. The just described construction of revolving doors requires a substantial space which normally militates against the installation of such revolving doors in a vehicle. Additionally, it is not necessarily assured that a revolving door provides the required pressure tightness. Such pressure tightness, however, is a requirement for the above-mentioned closing of a space in a sealed manner. Such sealing is necessary, for example to introduce into the space of the revolving door an incapacitating gas in order to actively eliminate the danger, while simultaneously avoiding introducing such gas into neighboring spaces such as the cockpit or the passenger cabin or any other passenger and/or crew accommodation.
U.S. Pat. No. 6,470,512 B1 (Lau et al.) discloses a revolving door used in an aircraft to control the access to a single shower cabin from at least two dressing cabins. Security features are not involved in the disclosure of the just mentioned U. S. Patent other than privacy considerations.